Jean Case of Fallbrook House, a Troy, Pa., business specializing in "everything I can sell in silk fiber," has put together a guide to raising silkworms. Among her pointers:

*Incubation. Eggs take an average of 11 to 14 days to hatch. Place them on brown paper in a shoe box. Keep them warm -- 72 to 80 degrees. Place a wet cotton ball in a paper cup to add humidity, and leave the lid ajar to allow air circulation.

*Hatching. Lay a few tender leaves over newly hatched worms. When they have crawled up, pick up leaves and move to another box.

*Feeding. Provide only fresh, crisp, dry mulberry leaves. Wet leaves will kill the worms. Wash leaves, dry quickly and store in refrigerator. For overnight feeding, lash five stems together with a wet cotton ball surrounding the cut ends and sealed with plastic wrap. For the first two growing cycles, the worms eat only tender young leaves, but then can survive on older ones.

*Spinning. After five growth periods totaling 25 to 30 days, the worms change color, stop eating and look for a place to shed their cocoons. Transfer the worms to a box with two-cubic-inch sections, or egg cartons or twig wigwams. Do not disturb for seven days. Then sort for reproduction and reeling.

*Reproduction. Save the best cocoons from the worms that grew fastest. Males are slightly smaller, lighter and more pointed. Save plenty to insure having both sexes.

*Reeling. The silk can be reeled immediately. If the cocoons are to be saved, kill the chrysalis inside either by steaming in a strainer over boiling water for 20 to 30 minutes, or baking in a 160-degree oven for two to three hours.

*Breeding. Line several small boxes with brown paper. Two to three weeks after spinning their cocoons, moths will emerge. Place pairs in boxes; cover with lids punched with airholes. Fertile eggs turn gray. Let rest for three days before storing.

*Storing. Keep eggs at 70 degrees until September. Store in the refrigerator over the winter in plastic bags -- do not freeze. In May, when the mulberry trees bud, pull them out, and the cycle begins again.

These directions are for the most common silkworm, the Bombyx mori, which hatches once a year. Other breeds of silkworms reproduce up to six times a season.

To obtain Jean Case's portfolio, which contains information on silk fiber, directions for reeling silk and silk samples, send $15 plus postage to Fallbrook House, R.D. 2, Box 17, Troy, Pa. 16947.

Other sources:*Mary Stock, 3811 E. Lincoln St., Canton, Ohio 44707. (216) 488-2544. Ships live worms. $5 for 50.*Marjorie Evans, 8233 Nada St., Downey, Calif. 90242. (213) 861-2608. Ships silkworm eggs. $5 for 100. *Kay Speakman of the Arachne Spinners, (301) 384-9561, and Nan Roche of the Moon Spinners, (301) 864-1805, have information on silkworms and weaving.

* Margaret Conant of Potomac Craftsmen Inc., (301) 577-2988, provides names of local weavers.